To enable remote xul apps stringbundles should be usable via http. Perhaps a new
attribute could be added to strinbundle, eg delayed, which controls whether the
resource will be loaded synchronously or asynchronously.

This bug is related to bug #26291 , which is about loading stringbundle async
for perf reasons. IMHO, the API should provide both methods and the XUL tag
should default to sync. I guess loading synchronized is 99% ok for local XUL,
but perhaps a problem for remote XUL.